I heard (unknown source) that using slightly thicker oil in your engine will lubricate it better, and it will last longer, and the reason car companies use thinner oil is for better fuel economy. Is this true, and if yes, what type of oil (other than the recommended 5W20) do you guys use in your 6s? Thanks.

I heard (unknown source) that using slightly thicker oil in your engine will lubricate it better, and it will last longer, and the reason car companies use thinner oil is for better fuel economy. Is this true, and if yes, what type of oil (other than the recommended 5W20) do you guys use in your 6s? Thanks.[/b]

It's true to an extent. I use 5w-30 synthetic most of the time, and people have reported acceptable UOA results with 10w-30, too. The fuel economy difference really is marginal, maybe 1%?

I heard (unknown source) that using slightly thicker oil in your engine will lubricate it better, and it will last longer, and the reason car companies use thinner oil is for better fuel economy. Is this true, and if yes, what type of oil (other than the recommended 5W20) do you guys use in your 6s? Thanks.[/b]

Nobody ever ever has a bad word to say about Schaeffer Supreme 7000 (but many have criticisms of other oils)

(footnote 1) OCI=oil change interval

(footnote 2) GC is German Castrol, a type of Castrol Syntec that is undoubtedly fully synthetic (apparently mostly esters -- Group V), sold in the United States only in AutoZone stores -- and not all of those -- and perhaps not for long. GC comes only in 0W-30 grade, and may be identified by "Made in Germany" on the back of the bottle.

Last fall, we switched from Motorcraft 5W-20 to GC (with a K&N HP-2010 oil filter), and ran it for 9,000 miles (I had planned on a 7,500 OCI, but lost track). The Mazda6s definitely felt different with the GC: for whatever reason, gearshifts in the 5-speed automatic transmission became all but imperceptible. The car felt very turbine-like and "honey" smooth. At the same time, raw acceleration seemed a bit more sluggish, and we lost a mile or two per gallon in fuel economy. Still, I might have continued with GC were it still available where we live, which -- at least temporarily -- it is not. (There are endless threads in the BITOG "Foreign Oil" forum about whether the availability issue is a temporary or a permanent one.) GC is a "thick" 0W-30: that is, it is almost a 0W-40, and the acceleration and fuel economy results we experienced are consistent with a heavier grade of oil.

This past week, we changed oil to Schaeffer Supreme 7000 5W-20. The difference in feel from the GC is quite distinct. The engine revs more freely than it did with GC, and the shifts in the ATX are detectable again. It is much too early to know the effect on fuel economy, but those who have used Schaeffer and posted their results on BITOG have seen fuel economy gains even when the oil they were switching from had the same viscosity grade as the Schaeffer oil they switched to. In the used oil analysis (UOA) forum of BITOG, Schaeffer oils consistently generate excellent reports.

not wanting to go off topic, but this gets my attention. My car has always been serviced by a Mazda dealership, and they've always used their OEM filter and 5-w20 oil. This was a service they provided for free for a full year, no questions asked. Now that it's over, I planned to go synthetic and use a K & N 2010, but the service manager(not the usual guy) told me it wasn't a good idea since he's seen a couple of 6's wasted due to poor oil filter and oil quality. Is he crazy? Like stated on some other thread, it doesnt drop below 90 here, so oil changes have to be done every 3k miles, and though maybe synthetic wild help reduce engine wear...Maybe the guy from Mazda is trying to squeeze some extra $$$ from me...

Thanks a lot for your help, I think we are going to go with 5W-30. I think it will protect the engine better than the 5W-20, but at the same time isn't too thick.

Note - My Dad always went one number up on oil in all his cars and they have always lasted a long time (good example is our 1985 Ford Merkur was 15 years and 236,000 miles old when we sold it and it was still running like new) Thank again for the help!

One of our company trucks lost an engine due to goin to a heavier weight oil. We use Fords for the most part and the tolerances are so close on the new ones that you can really jeopardize the engine. They also require a 5w-20 semi synthetic.
and i think the guy went either 10-40 or 10w-30. ITs been a year so i cant remember.

not wanting to go off topic, but this gets my attention. My car has always been serviced by a Mazda dealership, and they've always used their OEM filter and 5-w20 oil. This was a service they provided for free for a full year, no questions asked. Now that it's over, I planned to go synthetic and use a K & N 2010, but the service manager(not the usual guy) told me it wasn't a good idea since he's seen a couple of 6's wasted due to poor oil filter and oil quality. Is he crazy? Like stated on some other thread, it doesnt drop below 90 here, so oil changes have to be done every 3k miles, and though maybe synthetic wild help reduce engine wear...Maybe the guy from Mazda is trying to squeeze some extra $$$ from me...[/b]

This has been asked and answered before many times but I will give you my fill since I am here anyways. :P

He's probably just trying to feed you some BS so as to scare you in continuing to go to him for service, plus he might be old school and thinking of the very first synthetics on the older engines. Synthetics now-a-days are a good oil to use providing you keep with well known/quality brands, worse case is that they will be no better than the standard 5-W20 used by Mazda. Remember, all 5-W20 oil (motorcraft included) at the very least are a synthetic blend. I have yet to see a 5-w20 that has been pure dino oil. So technically the oil you are using is already half way there from being a pure synthetic.

As for the K&N Oil Filters, you are always going to have to have some compromise on flow rate vs. filter quality. K&Ns are decent oil filters that filter quite well but are really known for their high flow rate (mainly the bypass flow rate, one of the highest rated amongst filters). KN Oil Filters use a resin covered filter type media, I believe similar to the PureOne filters (which rate well too). This allows the filters to have a high flowrate yet still maintain a decent filtering quality. I have yet to have an issue with my KN filters and I have used them in my older 87 Honda Accord when I had that. The thing I enjoy about the filter the most is the welded nut at the end of the filter making it easy for removal in tight spots. And if you haven't looked under your car yet, you should. The amount of space available for filter removal is dismal at best. My first oil change I broke a filter wrench and punctured the filter upon removal attempt (Required jabbing a screwdriver through the filter and removing it that way). Of course it didn't help that the factory tightened too much and the plug too little (was able to remove plug with my fingers).
Paul

On a side note, where in Puerto Rico do you reside? The wife and I visited PR in June for the first time and loved it (Stayed at the Marriott in San Juan). We plan on returning again next year. I saw tons of Mazda3s but maybe only one Mazda6 when there. Oh, and I thought that I drove on scary roads (DC, 495 Beltway, 270, etc) but you guys take the cake! I loved seeing how one car stopped in the middle of the road and "backed in" to a one way garage to park, even though the entrance was the next turn. You guys are crazy! :P

The thing I enjoy about the filter the most is the welded nut at the end of the filter making it easy for removal in tight spots. And if you haven't looked under your car yet, you should. The amount of space available for filter removal is dismal at best.[/b]

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